Place cereal in a large bowl; set aside. Combine syrup and sugar in a saucepan. Bring to a boil over medium-high heat; cook 1 minute. Remove from heat; stir in peanut butter.
Working quickly, pour peanut butter mixture over cereal; toss lightly to coat. Drop by heaping tablespoonfuls onto wax paper. Let stand at room temperature until firm. Store in an airtight container.